Being treated as a mentally retarded person is never fun. If you are not comfortable telling the manager she is treating you like one, then be ready to speak up next time she is rude to you (especially in front of a customer). A response as suggested earlier is good: The issue here is coupon approval. The customer has been waiting for x minutes. Will you please expediate this? (If you can deliver this message with an icy tone, so much the better).
I would also jerk away with a scathing look when the manager touches you to ensure she gets your meaning.
A conversation would go better, but if the manager is really an idiot or you hate confrontations, then the above is what I would do. If you really want to stick it to her, when she does something mundane like putting something away, pat HER on her back and pay her a stupid compliment. Follow that up with an explanation that if she feels insulted, she shouldn't do that to you either.
